Application of High Speed Videography and Digital Image Processing Software to Assess Performance of Blasts In Opencast Mines: A Case Study

Abstract

Rock mass can be fragmented by the process of blasting in which a known volume of the yield is obtained by using a calculated quantity of explosive. The explosive selected for blasting depends on factors like rock mass parameters, blasting economics and blast design. Assessment of the performance of a given blast is essential in the larger economics of the mining project. A study was conducted to know the blast performance at two different mines. High speed videography was used to assess blast performance and wastage of gaseous energy. With the increase in stemming height from 1.0m to 3.5m, it was found that there is decrease in the escape of gas energy ejection from 7.42m height to 3.5m, which was almost half the height of ejection. The analysis showed that the maximum velocity of rock movement was found to be 8.97m/s in Mine-A and 12.40m/s in Mine-B with varying strength of intact rock mass. Wipfrag digital image processing software was used to determine the fragment size distribution, which gives quick and accurate measurements. Blast-4 of Mine-A with explosive charge of about 33.36kg/hole produced finer fragmentation compared to Blast-4 in Mine-B with same explosive charge, clearly showing influence of strength of rock mass.